Working tool with replaceable working bit

ABSTRACT

A replaceable wear part ( 13, 22, 22   a   , 32, 41 ) for mounting on a leading edge ( 12, 27 ) of a working tool ( 10, 27, 30 ), said leading edge and said wear part having co-operative guide formations ( 16, 18 ) extending generally perpendicular to the leading edge and which provide a socket and projection type of slidable inter-fit whereby the wear part can be driven by a force extending generally perpendicular to the leading edge in order to take-up a working position in which it is secured against displacement from the working position by frictional inter-engagement between the guide formations ( 16, 18 ) on the wear part and the leading edge, and without need for threaded or other separate removable fasteners.

[0001] This invention relates to a working tool with a replaceableworking bit, and also to the replaceable working bit per se.

[0002] The invention is concerned generally with a working tool, whichnecessarily is provided with one or more working edge or face which isdesigned to work on a particular material, and which therefore isexposed to wearing action over a period of time.

[0003] However, the invention has been developed primarily in connectionwith a working tool which is capable of working on soil or similarmaterial e.g. sand, gravel, stone, rubble, and which usually has aworking edge to engage the working material concerned. The working edgewill be subject to wear over a greater or lesser period of time,depending upon the required operation, and the material being handled.

[0004] In some blade-type of working tools, it is acceptable to carryout sharpening of the edge as it becomes worm, and this can be done anumber of times (by progressive erosion into the main body of the tool)but eventually the entire tool has to be scrapped. In other workingtools, it is known to provide replaceable working edges, which aresecured to the main body of the tool by threaded fasteners e.g. bolts orscrews, and which are sacrificial, in the sense that the working edgesprotect the main body of the tool from wear (which is the expensivecomponent), and which are replaced when an unacceptable level of wearhas occurred in the replaceable part.

[0005] In connection with soil working tools for use in agriculture,there are many examples of working elements or working “bits” which arereplaceably mounted on the main body of the tool concerned e.g. a“point” on the share of a plough, a knife on a plough body, or a tip ofa cultivator tine.

[0006] In all of these arrangements, it is usual to mount the workingelement in position by means of two separate threaded fasteners. Thisgives a robust mounting of the elements, and by reason of using twoseparate fasteners, the element is well able to resist any twisting orturning moments which may be applied to the element in service, inaddition to providing shear resistance to any direct forces tending toseparate the element from the tool.

[0007] Evidently, when it become necessary to replace a worn element,the two fasteners have to be released, and a replacement element theninstalled in place. If this is carried out “in the field”, this is atime consuming and difficult task, especially, as is often the case, thefasteners or nut fixings have become damaged, rusted or otherwise becomedifficult to release. The same will apply in respect of routinemaintenance carried out prior to use. In extreme cases, it is necessaryto use a cutting torch to release the fasteners.

[0008] Bearing in mind that a large cultivator might have up to sixtyseparate cultivator tines (each with its own replaceable tip), it can bea major operation to replace a full set of worn tips.

[0009] In extreme soil conditions e.g. heavy clay plus flints, a new setof cultivator tips can become worn within three hours and then needreplacement. A tractor to propel such large cultivators might cost ofthe order of £200,000, and is therefore an extremely expensive piece ofcapital equipment, and possible “downtime” of the order of three hoursrepresents a serious under utilisation of such a high capital cost item.

[0010] With a view to simplify the assembly and dis-assembly ofreplaceable wearing parts, it is known to provide a mounting arrangementon the main body of the tool which only requires a single fastener, butnecessarily this requires the provision of a suitably shaped seatingwhich holds the wearing part captive against rotation about the axis ofthe single fastener.

[0011] One example of such a known mounting arrangement comprises anassembly of a replaceable wearing part on a main body of a cultivatortine, in which the wearing part has a rectangular body which merges intoa V-shaped tip at one end, and on its opposite end it has a narrowprojecting lug. A single fastener is taken through the body and througha mounting hole in the tine, and a shaped socket or receiving recessalso in the tine receives the projecting lug in order to provideresistance to any turning action which may be applied in service to thetip and tending to rotate the tip about the axis of the fastener.

[0012] In this known arrangement of replaceable cultivator tip, there isstill the disadvantage of assembly and dis-assembly of the fastener, butin addition the projecting lug only forms a narrow prolongation of themain body of the tip i.e. the main-body is much wider than the lug, andthe lug is therefore the sole means of resisting turning forces appliedto the tip about the axis of the fastener. Therefore, this constructionrelies for its strength on the narrow lug, and on which highlyconcentrated stresses may be generated in service which may result inpremature failure.

[0013] The invention therefore seeks to provide a novel arrangement ofreplaceable wear part or bit for mounting on a leading edge of a workingtool, and which can be mounted in a working position on the tool, and besecured against displacement from the working position, without need forthreaded or other separate removable fastener(s).

[0014] According to one aspect of the invention there is provided areplaceable wear part for mounting on a leading edge of a working tool,said leading edge and said wear part having co-operative guideformations extending generally perpendicular to the leading edge andwhich provide a socket and projection type of slidable interfit wherebythe wear part can be driven by a force extending generally perpendicularto the leading edge in order to take-up a working position in which itis secured against displacement from the working position by frictionalinterengagement between the guide formations on the wear part and theleading edge, and without need for threaded or other separate removablefastener.

[0015] Therefore, a replaceable wear part according to the invention canbe driven e.g. by a hammer to take-up its working position, and theco-operative guide formations allow the wear part to slide in adirection generally perpendicular to the leading edge. The guideformations are arranged to exert a wedging action on the wear part, sothat the greater the distance travelled, the stronger will be thefrictional engagement forces acting between the guide formations.

[0016] In a preferred arrangement, the guide formations in the leadingedge of the tool form a socket whose width reduces with distanceperpendicularly inwardly of the leading edge, so that a progressivelyincreasing wedging force can act on a wear part as it is driveninternally of the socket.

[0017] The socket may be defined between a pair of opposed side wallswhich are convergent or taper, and the wear part has opposed externalside faces which are also convergent or taper, but to a greater extentthan the tapering of the side walls of the. socket, so that anincreasing wedging force is generated therebetween as the wear part isdriven to its working position, whereby also the frictional resistanceagainst possible displacement increases progressively.

[0018] The co-operative guide formations preferably also have aninterengagement which opposes any relative rotation of the wear partabout its longitudinal axis.

[0019] The walls or faces defining the guide formations may be ofmatching V-shape in cross section, though other cross sectional shapesmay be provided, such as to oppose rotation of the wear part about itslongitudinal axis, and relative to the leading edge.

[0020] Preferably, the invention comprises an assembly of thereplaceable wear part and the working tool in combination.

[0021] The wear part may comprise a working bit to be mounted on atransversely extending leading edge of an agricultural tool, such as a“point” (preferably a reversible point), a ploughshare, or a cultivatortine. However, the invention may be applied to other types of workingtool than agricultural tools e.g. an excavator bucket (front or rearmounted), or a loading shovel, each having a leading edge provided withexcavator teeth mounted thereon along the length of the leading edge, inwhich each excavator tooth comprises a replaceable wear part accordingto the invention.

[0022] Preferred embodiments of the invention will now be described indetail, by way of example only, with reference to the accompanyingdrawings, in which:

[0023]FIG. 1 is a plan view of a first embodiment of the invention inthe form of a ploughshare in assembly with a wear replaceable part, or“bit” which is force-fitted in order to take-up a mounting position inthe leading edge of the share;

[0024]FIG. 2 is a side view of the assembly;

[0025]FIG. 3 is a section taken on the section line A-A in FIG. 1, andshowing the engagement between the external side faces of a mountingportion of the wear part, and the side profiles of the socket defined inthe leading edge of the share;

[0026]FIG. 4 is a plan view of a second embodiment of the invention inthe form of a replaceable tine point tip for mounting on the end of atine, shown in exploded, unassembled form;

[0027]FIG. 5 is a side view of the tine point tip shown in FIG. 4;

[0028]FIG. 6 is a plan view of another example of tine point tip afterit has been driven to a working position mounted on the end of acultivator tine;

[0029]FIG. 7 is a side view corresponding to FIG. 6;

[0030]FIG. 8 is a cross section taken on the section line A-A in FIG. 6,and showing the slidable interengagement between the external side facesof a mounting portion of the tine point tip, and the side profiles ofthe socket provided in the leading end of the cultivator tine whichreceives the mounting portion;

[0031]FIG. 9 is a plan view of the leading end of a cultivator tine,showing the recess or socket which receives the mounting portion of thetine point tip (of FIG. 4 or 6);

[0032]FIG. 10 is an end view showing the side profiles of the socket;

[0033]FIG. 11 is a plan view of a third embodiment of the invention,showing a replaceable wear bit mounted (by force-fit) at the leading endof an inclined leading edge of a reversible point;

[0034]FIG. 12 is a plan view of a fourth embodiment of the invention;and,

[0035]FIG. 13 is a side view of the fourth embodiment.

[0036] Referring now to the drawings, there will be described preferredembodiments of replaceable working part or bit according to theinvention, and adapted for mounting on a working tool having one or moreworking edge or face which is designed to work on a particular material,and which is exposed to wearing action over a period of time.

[0037] The preferred embodiments which will be described comprise soilworking tools for use in agriculture, but it should be understood thatthe invention has wider application, and can be applied to replaceableworking bits per se, and to other types and combinations of working toolrequiring replaceable working bits to be mounted thereon, and withoutneed for threaded or other fasteners to assemble and disassemble thecombination.

[0038] Referring first to FIGS. 1 to 3, a first embodiment of theinvention is illustrated, and which comprises the combination of aplough share (and a replaceable wear part or “bit”), designatedgenerally by reference 10, and which has usual mounting holes 11 alongits lower edge, whereby the share 10 can be mounted on a plough, andwhen mounted in position, it is the transversely extending leading endor edge 12 of the share 10 which is the frontal part of the share andwhich first engages the soil during forward movement of the plough body.A replaceable wear part or bit, designated generally by reference 13, ismounted (by force-fit) in the leading end 12 of the share 10, so that ittakes up a working position, after being driven by a force extendinggenerally perpendicular to the leading edge 12 e.g. by a hammer. In theworking position, the wear part 13 is secured against displacement fromthe working position by frictional inter-engagement between cooperativeguide formations on the wear bit 13 and a suitable receiving formationprovided in the leading edge, and without need for threaded or otherseparate removable fasteners.

[0039] In the illustrated embodiment, a receiving socket 14 is formed inthe leading end region 15 of the share 10, and socket 14 is defined by apair of opposed profiled side edges 16 (see FIG. 3) which converge ortaper, as can be seen in FIG. 1, whereby a progressively increasingwedging action is applied to a projecting mounting portion 17 of thewear bit 13.

[0040] The mounting portion 17 has opposed external side edges 18, whichalso are convergent, but to a lesser extent than the convergence of theside edges 16 of the socket 14, whereby progressive axial movement ofthe mounting portion 17 inwardly of the socket 14 results in aprogressively increasing wedging action, and frictional force actingbetween the co-operative guide formations (the internal side faces 16 ofsocket 14 and the external sides 18 of mounting portion 17).

[0041] The wear bit 13 is made of suitable hard wearing material e.g.forged metal, and clearly the greater part of any wearing action appliedto the combination of the share 10 and bit 13 will be borne by the bit13, since it is the first part of the combination to engage unworkedsoil. The working forces applied to the bit 13 will generally tend toforce the mounting portion 17 still further into the socket 14, andtherefore during normal operation, there is no risk of the bit 13becoming dislodged from its mounting position. Evidently, any forcesapplied to the bit 13 other than axially extending forces, may apply aturning moment to the bit 13, but any rotation of the bit 13 in thesocket 14 will be resisted by the way in which the guide formationsinter-engage. Furthermore, any possible tendency of the bit 13 to rotateabout its general longitudinal axis 19 will be borne by the co-operativeinter-engagement between each external side 18 of mounting portion 17and the corresponding internal side edges 16. As can be seen clearlyfrom FIG. 3, each of the co-operative guide formations is V-shaped, andclearly the inter-engagement will be such as to strongly oppose anyrotational forces applied to the wear bit 13, about the longitudinalaxis 19.

[0042] In use of the combination of the share 10 and the wear bit 13,the share 10 will be exposed to wearing action as it moves through thesoil, but the major part of any wearing forces will be borne by the wearbit 13, and which will be made of suitable wear resistant material, andthis in combination with the robust but simple mode of mounting inposition, will mean that the wear bit is exposed to the major wearingaction, thereby prolonging the effective life of the share 10.

[0043] The wear bit 13 can be easily mounted in position, by simpleapplication of a driving force e.g. by a hammer, which force fits themounting portion 17 into the socket 14. However, the wear bit 13 will beexposed to wearing action over a period of time, and when anunacceptable level of wear has occurred, it is a simple matter todis-assemble the combination, by insertion of a wedging tool (not shown)between the inboard end 20 of the mounting portion 17 and the inner end21 of the socket 14. Therefore, replacement of a worn bit 13 can takeplace easily, either during routine maintenance, or in the field whennecessary, and without need to release threaded fasteners as used inknown arrangements.

[0044] Evidently, the combination shown in FIGS. 1 to 3, is a socket andprojection type of inter-fit, and in which the projection is provided onthe wear part 13 and the socket is provided in the leading end of theshare 10. However, these arrangements could be reversed, whereby amounting projection extends from the leading end 12 of the share 10, anda wear part with a receiving socket or recess can be driven onto theprojection. A similar wedging action, and also resistance to rotationwill be provided by the co-operative engagement between the respectiveguide formations.

[0045] Referring now to FIGS. 4 and 5, there is a shown a secondembodiment of the invention, applied to a cultivator tine (see alsoFIGS. 9 and 10), and replaceable tine point tip. The tip is shown inFIG. 4, and designated generally by reference 22, and having arectangular main body 23, and which is provided with a V-shaped tip 24at one end, and a rearwardly projecting mounting portion 25 at itsopposite end. The mounting portion 25 performs a similar function tomounting portion 17 of wear bit 13 in the first embodiment, and isdriven into frictional engagement in a socket or recess 26 formed in alower mounting end 27 of a cultivator tine (shown in exploded,unassembled form). The inter-engagement between the mounting portion 25and recess 26 is generally the same as in the first embodiment, andafter driving of the tine point tip 22 (which is a further example of areplaceable wear part or bit) to a working position in the recess 26,the frictional inter-engagement between the co-operative guideformations is sufficient to hold the tip 22 in the working position.Also, as in the previous embodiment, there is resistance to any turningmoments which may be applied in service to the tip 22, by theco-operative engagement between the guide formations.

[0046] An alternative type of wear part 22 a is shown in FIGS. 6 to 8,in assembly with a cultivator tine or other agricultural tool 27 a.

[0047] Referring to FIG. 11, a third embodiment of replaceable wear partor bit is shown, for assembly with a reversible point, designatedgenerally by reference 30. The point 30 has an inclined leading edge 31,and a replaceable wear bit 32 is driven e.g. by a hammer, to take up theworking position shown in FIG. 11, within a recess or socket 33 providedin the leading end region 34 of the point 30. Again, co-operative guideformations are provided on the opposed inner side edges of the recess33, and the opposed external sides of the wear bit 32, which providerequired frictional engagement to hold the wear part 32 in the workingposition, after it has been driven to the working position by axialsliding movement. There is also resistance against any turning momentsapplied to the wear bit 32 in service.

[0048] It should be noted particularly from FIG. 11 that the wear bit 32is located at or close to the leading edge region 31 a of the inclinedleading edge 31 of the point 30. Therefore, in practice, virgin orunworked soil will be engaged first by the leading end 32 a of the wearbit 32, and since the wear bit 32 will be made of a material which isstrongly resistant to abrasive action, it can have a long service life,and as it projects forwardly of the leading edge 31, even by a smallamount, it will be exposed to the greatest wearing action of theunworked soil, and which loosens the soil, and which then undergoesfurther working action by continued forward movement of the leading edge31.

[0049] The wear bit 32 is driven to the working position in the socket,and once an unacceptable level of wear has arisen, the wear bit 32 canbe removed by driving a wedging tool (not shown) between the inner endsof the wear bit 32 and the recess 33 in which it is mounted.

[0050] The embodiments shown in the drawings are examples of theinvention applied to agricultural tools, and replaceable wear parts orbits for use with such tools. However, the invention is applicable toother examples of working tools having a leading edge or face, exposedto a wearing action, such as the leading edge of an excavator bucket orshovel.

[0051] Usually, excavator buckets have digging teeth mounted along theleading edge, and at present the mounting of these teeth is by means ofthreaded fasteners, rivets and other similar fastenings. However, itshould be understood that the concept of replaceable wear bits, withoutuse of threaded fasteners, can be applied to digging teeth provided onexcavator buckets and the like.

[0052] A fourth embodiment of the invention is illustrated in FIGS. 12and 13, and comprises a holder 40, and a point 41 having a slidableinter-fit with the holder 40, by way of co-operative guide formations,and which allow the point 41 to be driven by a force extending generallyperpendicular to the leading edge in order to take-up a working positionin which it is secured against displacement from the working position byfrictional interengagement between the guide formations, and withoutneed for threaded or other separate removable fasteners.

[0053] The fourth embodiment shown in FIGS. 12 and 13 is generallysimilar to the other embodiments. Essentially, it comprises a holder ofthe type shown in FIG. 9, and a point of the type shown in FIG. 4. Theholder 40 is mounted on a tine 42, and the holder 40 is in two parts,comprising a main part 43 forming a central holder, and to which thepoint 41 is detachably secured, and a rear/upper holder path 44 which issecured to the tine 42 via a single bolt 45. However, to prevent thewear holder part 44 from rotating about the volt 45, and thereforewobbling in service. there is a sloping tongue 46 fitting into acorresponding notch or groove 47 in the main holder part 40.

1. A replaceable wear part (13, 22, 22 a, 32, 41) for mounting on aleading edge (12, 27) of a working tool (10, 27, 30), said leading edgeand said wear part having cooperative guide formations (16, 18)extending generally perpendicular to the leading edge and which providea socket and projection type of slidable inter-fit whereby the wear partcan be driven by a force extending generally perpendicular to theleading edge in order to take-up a working position in which it issecured against displacement from the working position by frictionalinter-engagement between the guide formations (16, 18) on the wear partand the leading edge, and without need for threaded or other separateremovable fasteners.
 2. A replaceable wear part according to claim 1, inwhich the co-operative guide formations (16, 18) allow the wear part(13) to slide in a direction generally perpendicular to the leadingedge, and are arranged to exert a wedging action on the wear part, sothat the greater the distance travelled, the stronger will be thefrictional engagement forces acting between the guide formations.
 3. Areplaceable wear part according to claim 2, in which the guideformations (16) in the leading edge (12) of the tool (10) form a socketwhose width reduces with distance perpendicularly inwardly of theleading edge (12), so that a progressively increasing wedging force canact on a wear part (13) as it is driven internally of the socket.
 4. Areplaceable wear part according to anyone of claims 1 to 3, and incombination with a working tool, in which the socket is defined betweena pair of opposed side walls (16) which are convergent or taper, and thewear part (13) has opposed external side faces (18) which are alsoconvergent or taper, but to a lesser extent than the tapering of theside walls (16) of the socket, so that an increasing wedging force isgenerated therebetween as the wear part (13) is driven to its workingposition, whereby also the frictional resistance against possibledisplacement increases progressively.
 5. A combination according toclaim 4, in which the co-operative guide formations (16, 18) have aninter-engagement which opposes any relative rotation of the wear partabout its longitudinal axis.
 6. A combination according to claim 5, inwhich the walls or faces (16, 18) defining the guide formations are ofmatching V-shape in cross section.
 7. A wear part according to any oneof claims 1 to 3, and adapted to be mounted on a transversely extendingleading edge of an agricultural tool, such as a point (30), a ploughshare (10) a cultivator tine (27), or a holding portion (27) of anagricultural tool.
 8. A wear part according to any one of the precedingclaims, and comprising a main holder 40 which is detachably securable toa tine 42, and to which a point 41 is detachably secured, and in whichthe holder 40 comprises two parts, namely a main holder part 43 and arear/upper holder part 44 which can be fastened to the tine 42 via asingle fastener 45, and which has a tongue and groove type of interfit46, 47 with the main holder part 40 to prevent rotation about thefastener, said rear/upper holding part also serving to act as a wearprotecting plate for the tine.